Power-operated doors



June 4, 1968 R. A. BUTLER ET AL 3,386,203

POWER-OPERATED DOORS 5 Sheets-Sheet 1 Filed Feb. 15, 1966 June 4, 1968 R. A. BUTLER ET AL 3,386,203

FIG. 2

June 4, 1968 A. BUTLER ET AL 3,386,203

POWEROPERATED DOORS Filed Feb. 15, 1966 s Sheets-Sheet 5 June 4, 1968 R. A. BUTLER ET AL 3,386,203

POWER-OPERATED DOORS Filed Feb. 15, 1966 5 Sheets-Sheet 4 June 4, 1968 R. A. BUTLER EYTAL 3,386,203

POWER-OPERATED DOORS 5 Sheets-Sheet 5 Filegi Feb. 15, 1966 United res Patent Q 3,386,2t33 PflWER-GPERATED DOGRS Richard A. Eutler, Cranham, Essex, Albert H. Haiier, Weybridge, Surrey, and Ramon Pcrera, llford, Essex, England, assignors to British Sterilizer Qornpany Lim ited, llford, England, a liritish company Filed Feb. 15, 1966, Ser. No. 527,585 Claims priority, application Great Britain, Fe .23, 1965, 7,741/65 lltl Claims. (Cl. 49-21%) ABSTRACT OF THE DESCLUSURE Door apparatus comprises a door frame defining a door aperture, a sliding door mounted for sliding movement across the door frame between an open position away from the aperture and a closed position covering the aperture, and being mounted so as to permit limited movement of the door when in the closed position substantially perpendicularly toward and away from the door frame. Clamps are mounted on the door frame at intervals around the door aperture to reciprocate substantially perp'endicularly toward and away from the door frame, and pads are provided on the door for engagement by the clamps. The clamps are connected to driving means to be reciprocated constantly by the driving means during sliding of the door, and that the pads are so arranged on the door that they are engaged by the clamps only when the door is in closed position. A constantly engaged geared positive driving means operates in common and simultaneously both the sliding of the door and the reciprocatin g movement of the clamps.

This invention relates to doors for power operation, such as by an electric motor, and has been developed for the doors of sterilizing chambers, used in hospitals and known as autoclaves, in which surgical dressings or other articles are placed and subjected to sequential conditions of high vacuum, saturated steam and again high vacuum to effect sterilizing steam penetration and then drying of the articles in one cycle of operation.

The invention will be described as applied to a sterilizing autoclave door but it is also applicable to other doors suitable for power operation and requiring secure closure,

for example industrial autoclave doors, watertight doors in ships and strong-room doors.

Door apparatus to which the invention is applied comprises a door frame defining a door aperture, a sliding door, door mounting means supporting the door for sliding movement of the door across the door frame between an open position away from the door aperture and a closed position covering the door aperture, the door mounting means permitting limited movement of the door when in the closed position substantially perpendicularly towards and away from the door frame, means for sliding the door and means for clamping the door closed against the door frame. According to the invention, geared positive driving means are provided for operating in common both the means for sliding the door and the means for clamping the door.

The provision of driving means in common has the practical advantage that a single motor can serve the two purposes of sliding and Clamping the door. What is more important however is that a geared positi e drive can either be made self-locking or involves movement of the whole system in the operation of any part. Consequently, high security is provided, by locking of the gear or the inertia of the whole system, against yielding or unclamping of the door when closed.

In a preferred embodiment of the invention, clamps are mounted on the door frame at intervals around the ice door aperture to reciprocate substantially perpendicularly towards and away from the door frame, pads are provided on the door for engagement by the clamps, the clamps are connected to the driving means to be rcciprocated constantly by the driving means during sliding of the door and the pads are so arranged on the door that they are engaged by the clamps only when the door is in closed position.

Conveniently, the clamps are C-clamps which extend around the edge of the door and are constantly reciprocated, by eccentrics on rotary shafts, as the door slides. Such external clamps at the near side of the door frame, past which the door slides to and from closed position, may be controlled to swing out of the path of the door, to clear the Way for the door to slide, and to return for clamping the door closed. Alternatively the clamps at the near side of the door frame could be internal clamps.

Preferably the door is suspended from an overhead track from which it hangs with limited freedom of movement, in its closed position, perpendicularly to its plane so that it can be pressed, by the clamps, to seal against the door frame in closed position.

A convenient drive comprises a rack along the head of the door meshing with a driving pinion mounted on the door frame, for sliding the door, and a set of rotary shafts outlining the door frame as coupling rods between the C-clamps, the shafts being interconnected at the corncrs by bevel or mitre pinions and driven by an electric motor, one of the shafts also driving the pinion for the door rack.

Other features of the invention are included in the following description with reference, by way of example, to the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic front elevation of a sterilizing autoclave with the door open,

FIGS. 2, 3 and 4 are respectively a plan, and side elevations corresponding to FIG. 1,

FIG. 5 is a front elevation of a constructional embodiment showing the door closed and also with parts broken away to reveal features of construction,

FIG. 6 is a part-sectional side elevation, on the line V1Vl of FIG. 5, showing the door suspension and the drive for sliding the door, and

FIGS. 7 and 8 are plan views corresponding to FIG. 5 and showing the door closed and partly open respectively.

The invention will first be described in principle with reference to the diagrammatic FIGS. 1 to 4.

As shown by FIGS. 1 to 4, an autoclave chamber 1 has a door frame 2 around the face of which is mounted an O-ring gasket 3.

A sliding door 4 is provided to seal the chamber 1 when moved across the door frame, to the right as seen in FIG. 1, and clamped against the gasket 3. The gasket 3 may alternatively be mounted on the door 4.

The door 4 is suspended from a fixed horizontal rail 5 by a pair of flanged rollers ti journalled in hanger brackets 7 and 8 which carry a horizontal rod 9 slidable in bearings in the brackets 7 and 8-.

A horizontal rack It is suspended from the rod 9 by a pair of lugs 11 and 12. A long helical compression spring 13 and a short helical compression spring 14 sheath the rod 9, at opposite sides respectively of the bracket 8. The long spring 13 is held, under some compression, between the bracket 8 and a stop collar 15, adjustably fixed on the rod 9, and the short spring 14 is held, but not under compression, between the other side of the bracket 8 and the ing 12. Thus, although the rack it) is carried by the brackets 7 and 8 on the door 4, the rack 10 can move slightly horizontally relatively to the door, the rod 9 sliding in the brackets '7 and 8, and can transmit horizontal movement to the door, thrusting through the spring 13 or 14 respectively according to the direction of movement.

The rack 19 is driven horizontally by a pinion 16 at the top of a vertical shaft 17 which extends behind the door frame upwardly from a reduction gear and reversible electric motor driving unit 18. By drive from the unit 18 in one direction or the other, the door 4 can be moved to slide on the rail across the front of or away from the door frame 2.

In order to seal the autoclave chamber hermetically, the door 4 must be clamped to seal against the gasket 3 and, to allow for the necessary small movement of the door perpendicularly to its plane, the rail 5 has a pair of notches 19 (FIG. 2) at which the flanged rollers 6 can slide laterally in the closed position of the door. The entry ends of the notches 19 are sloped so that, on commencement of opening movement of the door, the rollers lead the door slightly outwardly from the door frame for sliding movement clear of the gasket 3.

Clamping of the door 4 against the gasket 3 is effected by C-clamps 20 spaced at intervals along the top, bottom and sides of the door frame 2. The clamps 20 are operated by eccentrics on the vertical driving shaft 17 and counter shafts 21, 22 and 23 respectively at the top, bottom and far side of the door frame. The counter shafts are driven from the driving shafts by pairs of mitre pinions 24.

The clamps 20 are reciprocated constantly so long as the shafts are driven by the driving unit 18 but the movement of the clamps is idle except When the door reaches closed position and pads 25 on the outer face of the rim of the door become located behind the clamps. The driving unit motor is controlled by micro-switches so that it is switched off just after the door has reached closed posi tion and the clamps 20 have engaged the pads 25 to press the door against the gasket 3.

Although the clamps 2% move constantly backwards and forwards while the door is sliding, their spacing and cycle of movement are so co-ordinated in relation to the location of the pads that a clamping stroke of the clamps coincides with alignment of any clamp with a pad only when the door reaches closed position and each pad is then aligned with its respective clamp. Consequently, pads at the top and bottom of the door do not foul the clamps which they pass.

In order that the door shall not foul the clamps on the driving shaft 17 at the near side of the door frame, past which the door must slide, these near-side clamps are ganged together by a vertical rod 26 and the trailing edge of the door has a pair of arcuately-slotted cam plates 27 which engage the rod 26 and swing the clamps horizontally away from or into the plane of the door as the door commences to slide from or reaches its closed position.

The invention will now be described in more detail with reference to FIGS. 5 to 8 which show a constructional embodiment of a door, corresponding to that of FIGS. 1 to 4, and in which the same reference numerals denote corresponding parts.

The autoclave is designed to be housed behind a wall 28 (FIG. 6), for example in a recess in the sterilizing room of a hospital, and access for the user, to insert articles to be sterilized, is only through an opening 29 which can be closed by a sliding safety screen 30' suspended from a fixed rail 31 by rollers 32 on hanger straps 33. It is preferably arranged that the screen 30 must be closed by hand and that the electrical control apparatus of the autoclave cannot be energised until the screen 30 has been closed to operate a suitable switch. Thereafter, operation of the autoclave is controlled by the user from a pressbutton control panel on the outside of the wall 28. Means are preferably provided for locking the safety screen automatically until a sterilizing cycle has been completed and it can then be arranged that the safety screen opens automatically, such as through an electro-magnetic coupling, with opening of the autoclave door 4.

It is also preferably arranged that the leading edge of the autoclave door 4 has a safety switch, for example a hinged strip which operates a micro-switch (not shown), so that should the door encounter any obstruction in its closing movement the driving unit will be switched off.

The above and other safety precautions may be suitably embodied in an electrical control circuit which does not form part of the present invention.

The construction and arrangement of the clamps 20 can best be seen from FIG. 6. The respective rotary shaft, such as 23, is journalled at either side of each clamp in bearing lugs 34 mounted at the back of the door frame 2.

In a cylindrical eye 35 in the rear end of each clamp 26, an eccentric boss 36 on the shaft, between the bearing lugs 34, rotates to reciprocate the respective clamp backwards and forwards towards and away from the plane of the door frame 2. The clamps are restrained from rotation and guided linearly by each row of clamps at the top, bottom and far side being interconnected by a guide rod 37 of which the ends are engaged in elongated guide slots in guide blocks mounted on the door frame 2. One of the guide blocks 38 with its slot 39 is shown at the lower end of the guide rod 37 in FIG. 6. For the row of clamps at the near side, the rod 26 in the slots of the plate 27 serves the same purpose.

The outer end of each clamp 20 has a set screw 40' for fine adjustment of its clamping contact with the respective pad 25 on the door 4.

The driving unit 18 (FIG. 6) comprises a reversible electric motor 41, a reduction gear box 42 and an overload clutch 43 in the connection to the driving shaft 17. The gear box 42 preferably has a socket 44 into which a handle (not shown) may be inserted through a hole in the wall 28 to engage a shaft end 45 for manual operation of the drive in the event of electrical failure.

Since the driving unit 18 operates the clamps 20 as well as sliding of the door 4, it will be appreciated that some provision must be made to allow the driving shaft 17, and counter shafts 21, 22 and 23, to make a partial rotation to effect clamping or unclamping movement of the clamps 20 while the door 4 is stopped in its closed position at the end of its closing sliding movement or at the beginning of its opening sliding movement. This extra rotation is permitted by the spring 13.

When the door 4 reaches closed position, its sliding movement is stopped, by a convenient fixed abutment as described later, but the rack 10 can continue to move idly, compressing the spring 13 against the bracket 8 as the rod 9 slides through the bracket 8 (FIG. 7). In this movement, the lug 12 moves a short distance away from the spring 14.

In order to stop the driving motor 41, when the shafts have made their additional turn suflicient to operate the clamps 20 to seal the door 4, a micro-switch 46 is mounted on the chamber near the top of the driving shaft 17 and has a spring-loaded follower 47 which rides on the rim of a notched cam disc 48 on the top end of the shaft 17.

The notch 49 of the cam disc 48 receives the follower 47 once in each rotation of the shaft 17 but the microswitch 46 is so connected into the control circuit that it is by-passed and inoperative until the door 4 stops in closed position and operate a micro-switch (not shown) which arms the switch 46. The next time the notch 49 reaches the follower 47, the switch 46 operates to stop the motor 41.

At the end of a sterilizing cycle when the motor is started, in the reverse direction, to open the door 4, the rack 10 first moves idly, the lug 12 closing up to the spring 14, while the clamps 20 are moved outwardly to free the door 4 to move outwardly, due to the slope of the notches 19 in the rail 5, as it commences its opening sliding movement (FIG. 8).

The spring 14, which is short and stiff, forms part of a safety precaution in case the motor should be started to open the door while the chamber is still under vacuum. In such event, the resistance of the door to opening move ment would be very high, the bracket 8, being mounted on the door, would resist thrust by the spring 14 which would then be compressed, by the lug 12 moving with the rack 1i), sufficiently to allow operation of a micro-switch 50 mounted on the bracket 8 and operated by an abutment 51 projecting laterally from the lug 12. The microswitch 58 operates to stop the motor 41.

As a further precaution, means may be provided for positively holding the door in closed position and an example of one such means is shown on FIGS. 1, 3 and 4.

Projecting downwardly from the bottom left-hand corner of the door 4 is a stop plate 52 to encounter, when the door is closed, an abutment 53 which similarly projects downwardly from near the bottom left-hand corner of the door frame 2. Near the driving unit 18, the driving shaft 17 has fast therewith a collar 54 with a radial spur 55. The collar 54 is angularly adjusted on the shaft 17 so that after the door has reached closed position, the leading edge of the stop plate 52 has encoutered the abutment 53 and the driving shaft 17 has turned sufficiently for the clamps 21 to clamp the door, the spur 55 has turned into position against the trailing edge of the stop plate 52.

The spur 55 thus locks the door against any manual attempt to slide it open, being held by self-locking of the gears or the inertia of the whole driving system. The spur 55 also serves to check any rebound of the door as it closes.

A sterilizing autoclave chamber may be provided with a door as described above at each end so that the interior of the chamber is accessible for use from either end. The control system for such a double-ended autoclave is of course arranged so that the doors can be operated only in a safe sequence whereby, for example, material to be sterilized can be inserted at one end and only the door at the other end can be opened, after completion of a sterilizing cycle, for removal of the sterilized material for use.

We claim:

1. In door apparatus comprising a door frame defining a door aperture, a sliding door, door mounting means supporting said door for sliding movement of said door across said door frame between an open position away from said door aperture and a closed position covering said door aperture, said door mounting means permitting limited movement of said door when in said closed position substantially perpendicularly towards and away from said door frame, means for sliding said door, and means for clamping said door closed against said door frame, the improvement which comprises constantly engaged geared positive driving means for operating in common and simultaneously both said means for sliding said door and said means for clamping said door.

2. Door apparatus according to claim 1, in which said means for clamping said door comprise clamps mounted on said door frame at intervals around said door aperture and means for reciprocating said clamps substantially perpendicularly towards and away from said door frame, pads are provided on said door for engagement by said clamps, said means to reciprocate said clamps are connected to said driving means to be reciprocated constantly 5 by said driving means during sliding of said door and said pads are so arranged on said door that they are engaged by said clamps only when said door is in closed position.

3. Door apparatus according to claim 2, said clamps being C-clamps to extend around the edge of said door, said means for reciprocating said clamps comprising eccentrics on rotary shafts, certain of said clamps at a near side of said door frame, past which said door slides to and from closed position, being external clamps, to engage around the outside of the edge of said door, and means for swinging said clamps at said near side of said door frame out of the sliding path of said door and for returning them around the edge of said door for clamping said door closed.

4. Door apparatus according to claim 1, clamps mounted on said door frame at intervals around the door aperture, rotary shaft means interconnecting said clamps in series for operation thereof, and a driving motor connected to one shaft of sa d rotary shaft means, said one shaft also being connected to means for sliding said door.

5. Door apparatus according to claim 4, a spur on said one shaft and a stop on said door, said spur engaging said stop in the closed position of said door.

6. Door apparatus according to claim 1, a horizontal overhead track from which said door is suspended for horizontal sliding movement, a rack on said door extending parallel with said track and driving pinion means in engagement with said rack for sliding said door.

7. Door apparatus according to claim 6, and spring means loading said rack to allow limited horizontal movement of said rack relatively to said door.

8. Door apparatus according to claim 7, in which said track is notched to allow movement of said door laterally of said track when the door is in closed position.

9. Door apparatus according to claim 1, an electric motor connected to said driving means, and switch means for controlling said motor and operable by said driving means only when said door is in closed position.

10. Door apparatus according to claim 1 wherein said means for clamping said door comprise clamps mounted on said door frame at intervals around said door aperture, further comprising means for continuously madntaining at least some of said clamps in orientations always to limit outward movement of said door when said door is in the closed position, regardless of whether said door is clamped closed against said door frame.

References Cited UNITED STATES PATENTS 3,145,021 8/1964 Anderson 49-246 FOREIGN PATENTS 1,166,659 3/1964 Germany.

809,132 2/ 1959 Great Britain.

DAVID J. WILLIAMOWSKY, Primary Examiner.

J. KARL BELL, Assistant Examiner. 

